Sulphate ammonium N content:21% min Caprolactam grade Water: 0.2% max White flowing crystal Sulphate ammoniumAmmonium sulphate 21% ... .0Free acid(H2SO4)content,% ≤0.030.050.20Fe content, % ≤0.007--As content,% ≤0.00005--Heavy metal(Pb)content,% ≤0.005--Water insolubles,% ≤0.01 ... used in agriculture,it is not necessary to check the content of Fe,As,heavy metal and water insolubles. Sulphate ammonium